Hyperventilation syndrome

Hyperventilation syndrome.
Classification and external resources
ICD-10	R06.4 or F45.33
ICD-9	306.1
DiseasesDB	31118
eMedicine	emerg/270

Hyperventilation syndrome (HVS; also chronic hyperventilation syndrome or CHVS) is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply or too rapidly (hyperventilation). HVS may present with chest pain and a tingling sensation in the fingertips and around the mouth (paresthesia) and may accompany a panic attack.

People with HVS may feel that they cannot get enough air. In reality, they have about the same oxygenation in the arterial blood (normal values are about 98% for hemoglobin saturation) and too little carbon dioxide in their blood and other tissues. While oxygen is abundant in the bloodstream, HVS reduces effective delivery of that oxygen to vital organs due to low-CO₂-induced vasoconstriction and the suppressed Bohr effect.

The hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to fall below healthy levels, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the person to try breathing even faster, which further exacerbates the problem.

The respiratory alkalosis leads to changes in the way the nervous system fires and leads to the paresthesia, dizziness, and perceptual changes that often accompany this condition. Other mechanisms may also be at work, and some people are physiologically more susceptible to this phenomenon than others.^[1]

Causes

Hyperventilation syndrome is believed to be caused by psychological factors and by definition has no organic cause.^[2] It is one cause of hyperventilation with others including infection, blood loss, heart attack,^[3] hypercapnia or alkalosis due to chemical imbalances, decreased cerebral blood flow, and increased nerve sensitivity may also underlie this symptom.^[4]

In one study, one third of patients with HVS had "subtle but definite lung disease" that prompted them to breathe too frequently or too deeply.^[5]

Many people with panic disorder or agorophobia will experience HVS. However, most people with HVS do not have these disorders.^[1]

Diagnosis

Hyperventilation syndrome is a remarkably common cause of dizziness complaints. About 25% of patients who complain about dizziness are diagnosed with HVS.^[4] The gold-standard diagnostic technique is to have the patient breathe rapidly for two minutes. This will trigger the symptoms and convince the patient that overbreathing is responsible for the symptoms. This test can only be performed at a time when the patient is not already experiencing symptoms.

Treatment

While traditional intervention for an acute episode has been to have the patient breathe into a paper bag, causing rebreathing and restoration of CO₂ levels, this is not advised or taught.^[6] When patients hyperventilate, they change their blood chemistry toward alkalosis. In alkalosis, hemoglobin binds more securely to the oxygen ('alkalotic O₂ clamping', also called the 'Bohr effect'), so the patient's cells become relatively hypoxic. Restricting inspired oxygen worsens this hypoxia and is detrimental to the patient. If attempting to calm the patient does not work within a few minutes, and the patient's condition is deteriorating, the hyperventilation may be caused by a medical condition (some of which are life threatening such as head injuries or drug overdose).

The same benefits can be obtained more safely from deliberately slowing down the breathing rate by counting or looking at the second hand on a watch. This is sometimes referred to as "7-11 breathing", because a gentle inhalation is stretched out to take 7 seconds (or counts), and the exhalation is slowed to take 11 seconds. This in-/exhalation ratio can be safely decreased to 4-12 or even 4-20 and more, as the O₂ content of the blood will easily sustain normal cell function (for several minutes at rest) when normal blood acidity has been restored. However, if a few minutes of this intervention are not effective, the patient should be seen by emergency medical personnel (paramedics or physicians).

Most patients benefit from carefully, deliberately slowing down their breathing twice a day for five minutes at a time.^[4] The goal is to reduce breathing to no more than five breaths per minute. This helps retrain their habits and convince them that faster breathing is unnecessary.

References

1. ^ ^{a b} "eMedicine - Hyperventilation Syndrome: Article by Edward Newton, MD". http://www.emedicine.com/emerg/topic270.htm. Retrieved 2007-12-21. 
2. ^ Shu, BC; Chang, YY, Lee, FY, Tzeng, DS, Lin, HY, Lung, FW (2007-10-31). "Parental attachment, premorbid personality, and mental health in young males with hyperventilation syndrome.". Psychiatry research 153 (2): 163–70. doi:10.1016/j.psychres.2006.05.006. PMID 17659783. 
3. ^ "Hyperventilation". http://www.emedicinehealth.com/hyperventilation/article_em.htm. Retrieved 2007-12-20. 
4. ^ ^{a b c} "Neurology - Hyperventilation Syndrome | Brad McKechnie, DC, DACAN". http://www.chiroweb.com/archives/12/04/03.html. Retrieved 2007-12-20. 
5. ^ Natelson, Benjamin H. (1998). Facing and fighting fatigue: a practical approach. New Haven, Conn: Yale University Press. pp. 40. ISBN 0-300-07401-8. 
6. ^ Bergeron, J. David; Le Baudour, Chris (2009). "Chapter 9: Caring for Medical Emergencies". First Responder (8 ed.). New Jersey: Pearson Prentice Hall. p. 262. ISBN 978-0-13-614059-7. "Do not use a paper bag in an attempt to treat hyperventilation. These patients can often be cared for with low-flow oxygen and lots of reassurance"